This invention relates to a magnetic contaminant capture device and a method for use in applications requiring the capture and removal of contaminants from a moving fluid that can be in either a gas, vapor, mist, or liquid state. The invention is directed to various embodiments that include applications in recirculating fluid systems and single-use fluid systems. The invention has application in recirculating lubrication systems that experience degradation in performance due to mechanical wear induced contaminants, and premature deterioration of lubricating fluid.
In every industry, often continuously, various types of machines operate under heavy-duty loading conditions. All of these machines must be lubricated. Automotive engines, compressors, gearboxes and crankcases of all types, including transmissions and transaxles, are all subject to costly wear and damage. Proper lubrication and maintenance can minimize such problems. However, despite regular servicing of the lubrication systems, which includes changing myriad filters and fluids, considerable and sometimes catastrophic damage is experienced in such machines. That damage has often been deemed to be difficult, if not impossible to minimize. The primary cause of such damage has been well-defined and includes the wear resulting from metal surfaces moving against other metal surfaces, which creates metallic shavings, chips, and micron sized particles. The latter micron-sized, wear metal particles can operate as free metal catalysts that degrade lubricant effectiveness by oxidation of both desirable hydrocarbon chains and lubricity enhancing additives.
Lubrication of metal surfaces can substantially reduce wear and includes, among other methods, the application of surface coatings, interface materials, and petroleum-based oils and greases. In most machines, various types of oil and grease are used to lubricate the metal bearing surfaces that endure wear due both to metal on metal friction and to particulate abrasion. The former is generally controlled by periodic replacement of the lubricating fluid and, in some case, replacement or remachining of bearing surfaces. The latter is also controlled by regular changes of the lubricating fluid, but also primarily by filtration of circulating lubricants during operation.
However, another significant and harmful source of damage, which has been identified in recent years, results from the abrasive and catalyst effects of micron-sized particles and dust. In the past, these small particles have been known contaminants, but were deemed to be insignificant sources of wear; it was also not known that they attack the lubricity properties of the lubricants. Such contaminants are created under normal operation as wear and abrasion by-products of machine operation.
Various means have been employed to detect wear and damage to engines and machinery so that repairs and maintenance could be undertaken before catastrophic failure. One such means includes visual inspection of lubricant filters to detect debris and damaged components. Many types of equipment are also monitored using spectrographic analysis of the lubricant for purposes of detecting elemental components of frictional and abrasional wear by-products that are undetectable by visual observation. Other means of predictive wear analysis includes use of microscopes to count contaminant particles of various sizes, which can be indicative and predictive of failures of certain engine, machine, compressor, and gear box components. However, none of these sampling methods is all-inclusive, and the latter is ordinarily uneconomical and in some geographic regions, it is completely unavailable. Spectrographic analysis cannot identify potentially catastrophic failure due to chipped or otherwise damaged components, such as broken gear teeth, but it is useful for predicting wear patterns and in identifying drastic changes in the wear characteristics of equipment from one inspection to the next. A visual inspection is useful in detecting large metal shavings and a broken gear tooth, but it cannot identify the significant changes in wear patterns that predict major bearing surface failures. What is needed is a device that will augment these existing preventative methods while also incorporating the capability to capture and remove large shavings and broken pieces, as well as the smaller particles.
Those with skill in the art have known for some time that removal and replacement of lubricating fluid and real-time filtration is helpful to extending the life span of machine and engine components. It has only recently been discovered that even the best of removal and replacement operations and the best of filtration devices fail to remove highly damaging, micron-sized contaminants from the reservoirs, the fluid pathways, and the metal surfaces present inside such machines, engines, compressors, gear boxes and the like. Even if extremely thorough cleanings are accomplished during the removal and replacement of lubrication fluids, new particulate matter forms almost immediately upon renewed operation.
Most engines, gearboxes, and machinery do not incorporate filters capable of removing particles as small as 1, 2, and 5 to 10 microns from the lubrication fluid. This is primarily because such filters become clogged rapidly in pressurized, circulating lubricant systems, which can altogether prevent proper lubrication. In many types of gearboxes, such as, for example, various types of transaxles, a pressurized, circulating lubricant system is not practical from either an economic or operating workspace perspective. As a result, in such systems, even though lubricant is circulated during operation, there is no means to remove newly created debris and contaminants, except for isochronol removal and replacement of the lubricant. Here again, moments after a lubricant change, new debris and contaminants form upon renewed operation.
What has been missing from the art is a device that can work in conjunction with existing circulating lubricant systems and various types of machines and engines, which can augment existing filtration systems, and which can operate in the absence of any filtration system. Some attempts have been made in the past to create such a system. Fink et al. in U.S. Pat. Nos. 5,949,317 and 6,111,492 describes one such device. Fink et al. incorporates a magnet joined to an ordinary drain plug that is installed at the bottom of an engine crankcase oil pan. While Fink et al. maintains that claimed device attracts and captures magnetic particles from the circulating oil as it passes by the magnet, there are several shortcomings that prevent the concept from being effective in operation. First, when used in engines, which operate at high temperatures, the exposed magnet is susceptible to corrosion and deterioration of magnet strength, especially in engines operating at high diesel fuel temperatures. Even if coated as Fink et al. suggests, contact with abrasives and wear metals in the oil bath will destroy the coating and subject the magnet to oxidation and corrosion. If the corrosion resistant materials suggested by Fink et al. are used, only relatively low field strengths are available, which cannot capture a significant amount of debris and contaminants. If higher field strengths are desired, then rare earth permanent magnet materials must be used, which are highly susceptible to corrosion and damage in normal engine operating environments. Moreover, the rare earth magnets are also far more fragile and susceptible to fracture and damage under the high stress, high shock environments experienced in most engines, heavy-duty machinery, and gearboxes. Such magnet would not function in Fink et al.""s intended configuration.
Other attempts have been to monitor debris collection in a circulating oil system, such as that disclosed in U.S. Pat. No. 5,196,112, and to magnetically remove ferrous materials, such as the devices disclosed in U.S. Pat. Nos. 5,383,534 and 4,995,971. Each of these devices are capable of attracting and capturing, to some extent, magnetic contaminants from the lubrication fluid, but are limited to engines that have pressurized lubricant systems which move the oil past the magnet. However, none of these devices are compatible for use in machinery that lacks pressurized oil systems because higher strength magnets are needed, which can attract and capture contaminants from farther away in the lubricant reservoir than is possible in these previous systems. Here again, without higher strength magnetic materials and improved configurations of magnets, neither Fink, nor any of the other references are capable of effectively capturing and retaining an appreciable amount of contaminants from the oil.
Each of such attempts falls short of offering any motivation, suggestion, or description of a device that incorporates very high field strengths, effective flux patterns and densities, and corrosion resistance. Neither are such devices compatible for use in a wide variety of machinery, ranging from hotter running diesel engines, as well as highly-loaded gear boxes that lack pressurized lubricant filtration systems. While the previously known systems have been able to capture some of the magnetic contaminants from the lubrication fluid, they are not nearly as effective as the present invention in removing significant quantities of the smaller, micron-sized particles, and in permanently retaining already captured debris and contaminants. Moreover, experience with such devices has demonstrated many shortcomings in the prior art devices. Use of the instant invention has demonstrated, in stark contrast, surprising improvements in lubricant life span and wear characteristics of a variety of machines. In the absence of the device of the instant invention, it has been found that previously captured contaminants are often reintroduced into the lubrication system because of ineffective field strengths and flux line configurations. This shortcoming is especially pronounced in machines having pressurized lubrication systems and lubrication systems under high shock and duty load environments, which move the lubricant rapidly past the old magnetic devices. Without the new and novel device of the present invention, the captured contaminants and debris can separate and rejoin the lubricant pool.
What has been needed but heretofore unavailable is a device that significantly improves not only the capture and retention of contaminants and debris contained in the lubricant, but a device that maximizes the life-span of the lubricant and that minimizes the wear of not only engines, but also various types of machines and gear boxes. In addition to offering major operational advantages over the prior art, such a device must also be inexpensive to acquire, simple to operate, compatible for use in a wide range of environments, and easily manufactured so as to make the device available to the widest possible base of machine and engine operators.
The present invention meets these and other needs without adding any complexity, inefficiencies, or significant costs to operation of the most commonly used engines, machines, and gear boxes. The various embodiments of the present invention disclosed herein are readily adapted for ease of manufacture, low fabrication costs, and immediate compatibility with such equipment that is presently employed in the field.
In general, the present invention is directed to a magnetic contaminant capture device and method for use in applications requiring the capture and removal of contaminants from a moving fluid, which can be in a variety of thermodynamic states. The invention is directed to various embodiments that include applications in recirculating and single-use fluid systems. A contaminant capture device is contemplated that is adapted for immersion in a circulating fluid that is contained in an enclosed reservoir space. The fluid is not necessarily arranged to flow in a re-circulating fluid path, but can be moving randomly about in the reservoir space during operation of an engine, machine, compressor, or gear box. The reservoir includes a wall that is formed with an opening, typically a fill, observation, sample, or drain port.
The device further includes an installation cap configured to be removably installed into the opening in the reservoir enclosure. Typically, a non-magnetic, generally cylindrical capture element is joined to the installation cap and configured to have a substantially smooth finish on the exterior surface. The capture element also includes an interior longitudinal recess than can also be generally cylindrical.
A plurality of cylindrical permanent magnets with generally planar ends is received within the recess in a stacked arrangement. Each magnet includes opposite north and south seeking poles at the flat ends and is separated from another in the stack by at least one non-magnetic spacer. The spacer occupies the interface between the ends of the magnets, which is termed the pole interface. In this embodiment, the magnets are arranged so the respective north poles confront each other at the pole interfaces. In this configuration, the confronting poles creates flux lines that are deflected from their normal orientation and outward from the pole interfaces at an increased distance and in a direction generally orthogonal to the longitudinal axis of the magnet stack. The deflected flux lines also have an increased flux density relative to the flux density at regions distal to the pole interface and between the poles of a single magnet of the plurality.
The increased distal reach of the higher-density flux lines, in turn, increases the quantities of magnetic contaminants in the circulating fluid that would otherwise be attracted to and captured on the exterior surface proximate to the pole interfaces. This increase attraction and capture capability has been shown to be greater than the contaminant quantities captured on the surface of the capture element in the region between the pole interfaces. Also, this arrangement has proven far superior to that demonstrated by the prior art single element magnet.
The present invention further contemplates a variation wherein the contaminant capture device incorporates magnets that are formed from a permanent magnet material having a Curie temperature of approximately at least 310 degrees centigrade, a maximum flux of at least 10,000 Gauss, and a coercive force of at least 9,000 oersteds. Alternatively, an electromagnet arrangement can be used wherein the magnets in the stack are augmented with or replaced with a ferrous material that is wound with an appropriate number of turns of suitable wire whereby the desired maximum flux is achieved. The permanent magnets may also be simply augmented with windings of an electromagnetic coil that can be energized to boost the overall field strength and flux density of the arrangement. In another variation of the preceding embodiments, the capture device incorporates permanent magnets that are formed from a neodymium, iron, boron alloy that has an operating temperature of approximately at least 150 degrees centigrade. Alternatively, the magnets are formed from a samarium cobalt alloy having an operating temperature of approximately at least 300 degrees centigrade. Various physical configurations are also contemplated wherein the plurality of magnets includes at least 3 magnets each having a diameter of approximately 0.75 inches or more, and a height of approximately 1 inch, or more. Additionally, the contaminant capture device is configurable wherein the plurality of the stacked magnets and the capture element are formed to protrude, from a proximate end joined to the installation cap, approximately at least 3 inches or more to an opposite distal end.
The present invention is also directed to a variation of the preceding embodiments wherein the contaminant capture device incorporates a non-magnetic, generally cylindrical capture element that is joined to the installation cap at a proximate end. The exterior surface of the capture element includes a substantially smooth finish and has a longitudinally extending interior recess. Here again, a plurality of cylindrical permanent magnets is stacked together and separated by non-magnetic spacers at pole interfaces and received within the interior recess. Each magnet has opposite north and south poles at generally planar ends. The magnets are arranged so that the north poles confront each other at the pole interfaces, whereby the resulting flux lines deflect outward from the pole interfaces with increased flux density relative to the flux density at regions distal to the pole interface, and at regions between the poles of each magnet. In this embodiment, each magnet of the plurality is selected to have different field strengths and the magnets are stacked in order of increasing field strength from the proximate end to a distal end of the capture element.
In another variation of the preceding embodiments, a contaminant capture device includes the previously described elements and at least three cylindrical permanent magnets that are stacked together, separated by non-magnetic spacers at the pole interfaces, and received within the interior recess of the capture element. In this configuration, the confronting north poles create far reaching flux lines extending from at least two pole interfaces, each with increased flux density relative to the flux density at other regions. The added number of interfaces creates additional regions that can attract and capture the previously described increased quantities of magnetic contaminants from the circulating fluid.
In a different configuration, a contaminant capture device is contemplated that incorporates a non-magnetic, generally cylindrical capture element joined at a proximate end to an installation cap and configured with a distal end, a substantially smooth finish on the exterior surface, and a longitudinally extending interior recess between the ends. Also included, is a plurality of cylindrical permanent magnets that are stacked together and separated by at least one non-magnetic spacer at at least one pole interface. The stacked magnets are received within the interior recess. Each magnet is formed with opposite north and south poles at generally planar ends. The magnets are arranged with the respective north and south poles confronting each other at the pole interfaces. Here, the density of the flux lines emanating from the distal end is greater than the density of those flux lines spanning the distal and proximate ends. In this variation of earlier embodiments, the magnets of the plurality are each selected to have different field strengths and are arranged in order of increasing field strength from the proximate end to the distal end. As a result, the quantities of magnetic contaminants in the circulating fluid that are attracted to and captured on the exterior surface proximate to the distal end is greater than the contaminant quantities captured on the surface of the capture element in the region between the distal and proximate ends.
In operation, the present invention contemplates a method of using the contaminant capture device of the instant invention. The method is directed to using a capture device for removing contaminants from a circulating fluid that is contained in a machine that has an enclosed reservoir space that includes a wall formed with an opening. In the first step of the method, a capture device is selected that is adapted to be immersed in the fluid. The selected device incorporates an installation cap configured to be removably installed into the opening in the reservoir enclosure. Also included, is a non-magnetic, generally cylindrical capture element that is joined to the installation cap and configured with a substantially smooth finish on the exterior surface and with a longitudinally extending interior recess. Received in the recess are a plurality of cylindrical permanent magnets that are stacked together and separated by at least one non-magnetic spacer at at least one pole interface. Each magnet has respective opposite north and south poles at generally planar ends. The magnets are arranged so that the north poles confront each other at the pole interfaces, so that the resulting flux lines are deflected from their otherwise normal positions and generally outward from the pole interfaces in a direction orthogonal to the longitudinal direction of the recess and the stack. The rearranged flux lines also experience an increased flux density relative to the flux density at regions distal to the pole interface and between the respective poles of each magnet. In this configuration, the quantities of magnetic contaminants in the circulating fluid that are attracted to and captured on the exterior surface proximate to the pole interfaces is greater than the contaminant quantities captured on the surface of the capture element in the regions between the pole interfaces.
In the next step, the capture device is installed into the opening of the reservoir to protrude into the reservoir space for a period of time that includes operation of the machine. During the period of operation, the circulating fluid passes proximate to the capture device whereby contaminants, including shavings and ferrous particles, are attracted to and captured by the capture element.
Lastly, the capture device is removed from the opening during a period of non-operation of the machine. The retained contaminants are removed from the capture element, and the capture device is cleaned before reinstallation.